Vol. XI] 



COLE AND LOVETT—LIST OF OREGON DIPTERA 



343 



948. Ochthiphila juncorum Fall. 

 Hood River, VI-28 (Cole). 



949. Leucop^is griseola Fall. 



Hood River and Forest Grove, VI (Cole); Corvallis, 

 VII-6 (Lovett) and V-24 (Bridwell). This species is 

 aphidophagous and was observed in the larval stage feeding 

 on the vetch aphis at Forest Grove. 



Family HIPPOBOSCID^ 



Fig. 54. Olfersia americana (Leach). 



This peculiar group is quite different from any other in 

 the Diptera, as we commonly think of that order. The 

 adults are leathery in texture and resemble ticks. Some 

 species are wingless and a few pass through the winged 

 stage and lose these appendages. Most of the species are 

 parasites on the bodies of birds. The horse-tick probably 

 does not occur in North America. The sheep-tick occurs all 



